Getting out and exercising in winter, when the nights draw in, it's colder and motivation is lacking can prevent you getting you out of the front door. Going on you normal run or local group exercise session can be difficult but remember that exercising in cold environments burns more calories.
This is because your core temperature remains the same, rarely moving 1 degree away from the average body temperature of 36.2 degrees. In order to achieve this when the environment is much colder than our core temperature, heat promoting mechanism are activated, all exchange of heat happens through radiation, conduction, convection and evaporation. Your shell acts like a temperature gauge & a warning system for this heat promoting mechanism allowing them to trigger when shell temperature drops.
The cold makes us work
One of the first things we notice when it's cold is that our extremities (hands & feet) become cold, this is due to blood being diverted away from the shell of the body towards internal organs to maintain core temperature. As a result of colder temperatures, metabolic rate is increased generating more heat.
"your body burns more calories when it's cold to maintain core body temperature"
Exercise in itself is a heat promoting activity generating more heat (this requires calories to be burnt) to raise both core and shell to a normal operating temperature. We don't always feel like exercising however when it's cold, it's the best thing we can do to feel warm and comfortable again, this means less time chatting to your neighbor walking his dog before your run, and active recovery rather than inactive rests. This all adds up to an increase in calorie consumption.
Wrap up warm, you will likely shed layers once you get working and enjoy the benefits of a brisk morning run or an outdoor training session.